Bifacial Solar Panels - The BEST Solar Panel? Real World Results!

[@polarkerr]

I attended a Canadian Solar demo class on these bifacials and even their experts didn't do a better job explaining how good these panels compared to your explanation, Keep up the good work buddy.

[@ProjectsWithDave]

Wow, thanks!

[@pblackcrow]

@@ProjectsWithDave it's worth test it out. Also, try spray painting gravel white and silver. Because it will reflect differently.

[@pblackcrow]

If you give me credit, please change remember to change my last name to Gardner. I am getting ready to do make it official soon.

[@shaneclk9854]

Mirrors onthe ground

[@VeryWarmBear1]

Cover sheets of plywood with reflective Mylar and arrange them low behind the bifacial panels to see how much more power it can generate.

[@Bob-cx4ze]

Cement board won't rot

[@richardbutler1216]

Hello Dave, I wanted to say a massive thanks for all you have tough me regarding solar. I now have my system up-and-running. I changed plans several times as each video you posted made me re-evaluate. I now have 64 bifacial panels on 4 ground racks of 16 per rack. I have done as you suggested and placed two racks at 45 degrees from due South. One at 135 degrees SE and one at 225 degrees SW. The remaining two are due south. All have an azimuth of 36 degrees. The resulting performance is way beyond my expectations, interestingly, the SW panels produce half the power that the SE array produce in the early morning. This must be just from the back side of the SW panels. So pleased I changed my mind and went with the Bifacial panels. I also followed your advice and split the load on each of my two inverters by running racks 1 & 3 to the first and 2 & 4 to the second. I knew nothing about electrics before I embarked on this project, let alone solar! None of this would have been possible without the education you have given me. The clear and concise way you explain the process has been invaluable. I am in your debt. Keep up the good work. Regards, Richard.

[@ProjectsWithDave]

Richard, thanks for the encouraging feedback! I love that you have taken all the things I've learned from my install and analysis and made a much better solution than I did for my original install. I'm so glad my information could make a difference for you!!

[@PandorasFolly]

Hey Dave! Great video. I'm in New Mexico and I know a guy who did a neat trick with his bifacials. He mounted them as a pergola roof about 15 feet up. And on the ground he put down white concrete unnder the panels and white gravel 20 feet out from the panels. He said he saw a notable increase when he added it.

[@ProjectsWithDave]

Nice idea! Thanks for posting.

[@eastcorkcheeses6448]

I picked manderins years ago ,and they had a white geo-textile pinned under the trees specifically to reflect light to the underside of the trees - and help the fruit rupen quicker , same thing really .. Wether you'd want thousands of acres of plastic fabric everywhere is another issue though ..

[@glennmartin6492]

If the PVs were on a slanted mount on top of a roof I imagine colouring the roof white would increase panel efficiency AND cool the building.

[@coyotesden]

I've had my bifacials installed on our offgrid property for a little over 6 months, I'm getting much better performance than I expected.

[@r.b.l.5841]

I used Canadian Solar 440 bifacials and put them above a galvalume metal building (low slope) roof, with a racking system that allows me to tilt up for winter, and down for summer, in both cases my panels are well above the metal roof. Being near the 49th parallel, the panels have sun Behind them for a good stretch of the year, and lots of reflection during winter. My best production ever is acturally January and February when it is cold, and lots of reflection from snow and metal roofing. Yeah those high production numbers are only for a few hours per day, but when you need every watt, this is important. I have seen over 115% of rated capacity on many sunny cold days. One thing to be careful with - Put your framing only inline with the panel edges: no strut running in the middle of the PV back side! keep all the wires and any conduit or wire way away from anywhere they can cause shadows!

[@ProjectsWithDave]

Thanks for posting your actual experience!

[@jacobsmithjr]

That was the most comprehensive presentation I've ever seen! Although I'm not that great at math, I understood your explanation perfectly. Well done sir!

[@ProjectsWithDave]

Thanks! Glad it was helpful!

[@richardbutler1216]

Thank you for another great video. I am installing a ground mount system right now. One thing you did not mention was Bifacial racking, I managed to change my order for racks that are specifically designed for Bifacial and have no supports crossing the back of the panel. They adjust to the panel size. I was also able to get new Longi 445W Bifacial panels for only a few €’s more than the same watt standard panels. Interestingly, the Bifacial come with a 30 year performance warranty as opposed to the standard Longi panels 25 years.

[@ProjectsWithDave]

Thanks, good point! I did forget to mention the racking considerations. I think they can offer a longer warranty because they start at a much higher output with the backside boost and the backside glass is a better material then the typical back sheet.

[@tmathison66]

Outstanding content. Conclusions on bi-facial panels I've had to piece together from a myriad of sources...almost all confirmed in one video. I think the only belief not specifically confirmed has to do with backside gain being able to heat panels enough to shed snow cover on the top side from the heat produced by power generation entirely from the back side. Ground-mount panels set to a steep winter angle for a lower sun should automatically shed snow early in the day and provide substantially more power than panels with cells only exposed to light from the snow-covered top side - all with no manual snow removal activity.

[@ProjectsWithDave]

Thanks! Yes, come winter I will have results on snow, steeper angels and roof installations.

[@stevemarquardt3217]

For best radiance, make sure the reflective material is curved [to gather more IR] and farther away from the back of panel. Ideal IR would be a hemi-spherical 'cup' that will be focused towards the center of the array.

[@sf4137]

IR is waste in these types of panels - we want the visible spectrum. IR actually inhibits performance.

[@nikolaskallianiotis8622]

Bifacials are highly recommended when installed on flat rooftops without tiles painted white and always installed on angle (this is the case for many buildings in southern Europe). They are very efficient when the surface behind them is reflective.

[@ProjectsWithDave]

I imagine that would be much better than mounted flat on a roof, but it would require more racking equipment to achieve that.

[@nikolaskallianiotis8622]

@@ProjectsWithDave In that case you stick with the normal half cut, mono PV. I mean, if racking costs double the money just to put some bifacials, it's better to avoid them. Watching your video experiment regarding panel orientation, I'm thinking of using a couple of big power output bifacials in EAST-WEST direction for harnessing sun early in the morning and late in the evening, especially during winter. That's I think is a more appropriate and efficient way to use these panels if you can't install them the right way.

[@ProjectsWithDave]

Based on my most recent analysis, I think the best orientation would be SSE and SSW. You can see those results here: kzbin.info/www/bejne/gGjbn4xuaaibZ6c

[@nikolaskallianiotis8622]

​@@ProjectsWithDave Yup, I know...

[@richardoder3459]

I use twin 3120 watt bifacial arrays on dual axis trackers and during the summer I maxed out at just under 6700 watts. I placed the white granite rocks under my panels in order to catch as much reflection as possible plus my panels are elevated so I get reflective light from all angles.

[@ProjectsWithDave]

Nice! What tracker do you use?

[@richardoder3459]

@@ProjectsWithDave I built them myself out of 4” drill stem, cost around $1,000 including the electronics.

[@ProjectsWithDave]

Cool! Sounds like a great project!

[@danielnicholls6868]

should lay your bifacials on there side. keep panels a little more vertical and step each row back the width of panel.[like a set of stairs] you should get a reflection from front of second and third rows plus less snow in winter. would be nice to see thanks. make your stand a just forward or back for summer or winter

[@richardbutler1216]

So one thing I read somewhere is that you should consider increasing the tilt angle from the ideal at your latitude by 5 - 8 degrees and also raise the mounts as high as you can. They also said that you should increase the ground area below the back of the panels you cover with something reflective, like white stones.

[@ProjectsWithDave]

Since the power boost is going to have the biggest increase in mid summer it makes sense to adjust the tilt angle to favor winter production, that would result in a more even production throughout the year. Another advantage of bifacial! If you have a link to the information you read feel free to post it here. Thanks!

[@mohd.saifullahmajid6029]

What about water for the reflective back surface?

[@vlogsdeqayam612]

Excellent explanation!❤. Now I have made my mind to go with bifacial. greetings from Pakistan

[@stephenmabry2866]

To get more benefit from the backside of the bifacial panels, you could apply something shiney ( foil on foam, foil tape, etc ) and mount it on plywood. Then install the plywood behind the bifacial panel mounting rack so that at peak sun reflection, the plywood+foil sun reflection hits back side of the bifacial panels.

[@Studio52Dallas]

Just found this video so I'm a little late to the party. But, I can attest the Blue Sun 460-bifacial panels are awesome. We put 12 on top of our barn with S5 Protea brackets above very light colored AG panel and the results are incredible. Actually a bit too good to believe. Last weekend, just before peak sun, with only 6 of the panels turned on, our Growatt inverter read it was receiving 122 watts @ 30 amps from the 6 panels. If that's truly the case, we're just over 600w per panel. I need to touch base with Signature Solar to see if that's even possible. Or possibly it's reading incorrectly. Either way, we're generating all the power we need. Thanks for making awesome videos!

[@ProjectsWithDave]

Thanks for the feedback! I'm glad they are working well for you. You would not be getting 600W from 460W panels. Probably no more than 529W best case.

[@zmarko]

Great video Dave! A lot of helpful info here, especially for someone new trying to decide what works best for them.

[@ProjectsWithDave]

Thanks! Glad it was helpful!

[@HansFrisk]

Maximizing bifacials ideas: Dolomite gravel as ground cover underneat, in the same fashion: Marble gravel under the panels, both reflect significantly more light from the ground. A even more expensive option is the white reflective paint used for road lines, tumble any rock in a bath of that paint and a highly reflective and durable ground cover will be produced.

[@cojakiki3631]

I was planing on polished aluminum sheets, but this paint made me re think

[@tommak6516]

The thought of something reflective under the panels is so obvious why was it not tried? What are we missing?

[@HansFrisk]

@@tommak6516 only those last 15% or so of extra efficency you can squeeze out of the double sided panels. Been doing some trials for "winter electricity" with 90 degree "standing" panels and reflective white paint on the wall behind them, roughly 1.5 meters distance also the ground 0.5 in front and spacing them with 1.5 panel-width gaps to the next in the row (chucked up 10 of them for testing purposes against a barn wall painted in reflective paint roughly 3m up the wall) Panel size where 2.2mx1.2m (largest bifacials I could find).

[@HansFrisk]

@@tommak6516 forgot to mention this is at 56 degrees North latitude, further south this will have to be recalculated for different sun heights ofc.

[@ChrisDIYerOklahoma]

GREAT video. I am in the process of upgrading two of my arrays to Q-Cell 480w bifacial panels. I have one array done and can say the performance of bifacial has def improved vs my older Renogy 100w panels...esp in low light (cloudy conditions). My arrays are all ground mounted.

[@ProjectsWithDave]

Yes, I think the cloudy performance is the best selling point. Those are the times when you need the boost.

[@SolarTechFL]

I just added 13kw of q cell 480w bf to my offgrid system they are great panels. 36kw of pv now

[@TheSoupier]

I bought a bifacial panel for my sienna and it puts out WAY more power than my monofacial. Reflection off of my paint is a huge boost.

[@chrisrichardson8908]

You should do a video between micro investors, optimizers, and 1 charger/installer that you put in the house . Would love to know which one performs the best and gives you the best efficiency

[@ProjectsWithDave]

I already have plans to do a back to back comparison with NEP Micro inverters and the SolarEdge optimizer system in the future.

[@Bozemanjustin]

Yes I had an idea as soon as I heard about by facial solar panels They make a paint that is so white. It actually keeps the surface underneath it 15° cooler than ambient temperature So simply paint the concrete slab underneath your solar panels with that ultra white paint and you would probably get a copious amount of bounce back

[@mungewell]

Great description and analysis. Considering these to refurb my ground mounted system. Season tilt for Lat 50 means they are almost vertical, slight hill and snow behind the panels would mean quiet a boost. Also -40'c has significant effect, watch out for your Voc Max!

[@ProjectsWithDave]

Sounds like a good application for bifacials.

[@optionstrader9637]

It's nice to see an actual in depth comparison of bifacial to standard panels. I too live in ohio and plan on doing solar at home but im waiting on the paperwork side of things and ive missed out on panels and inverters so far because of it. But my plan is now to get 20 445watt canadian bifacials, two sungoldpower sp6548 inverters, 30kwh eg4 lifepower4 to run my whole house. The array is going to be mounted at 45° because i have a friend right down the road and he gets the best all around output at that angle and it should shed snow decent. Im going to have ac input with the inverters if/when my solar cant run the whole house in the summer bc the 3 ton ac unit. I use around 45-60kwh a day(summer) so im guessing it'll handle it.

[@ProjectsWithDave]

I think the steeper angle is a good choice to maximize winter production. However, if your max consumption is in the summer, you may want to go with 30 or 40deg.

[@rdlspmg6752]

Man you must be super happy with yourself for producing such monster Size boys at the very least man KUDOS to you I would be and I have 10 410w bi Facial panels from signature solar I’m drawing a blank right now on the manufacture name but I have yet to mount them so when I seen this title I had to watch this asap thank you so much for taking the time to make these awesome info packed GEMs 💎 that anyone thinking about doing solar for themselves or others can’t go wrong starting with your content

[@ProjectsWithDave]

Thanks, I appreciate that! It is a lot of work to take all the data and produce meaningful results, so I'm glad it was helpful for you.

[@RadioChief52]

I'm planning on dipping my toes in a small off grid system to keep the freezers and computers going and these panes are intriguing as I was thinking of installing them on a galvanized roof of a metal building. The south facing roof pitch is only 2 degrees so I would use a little more tilt on the panels to allow the morning and late afternoon sun to bounce off the shiny roof and onto the back of the panels.

[@ProjectsWithDave]

If you plan to elevate the panels off the roof at a diverging angle, I think you will see a noticeable benefit from the reflection. I think you would need 18" to 24" at the back edge to see a significant contribution.

[@kimmer6]

I did just that. My battery pack runs 2 full sized 24 cu ft self defrosting refrigerators, an old 24 cu ft upright freezer and a 5 cu ft chest freezer. I bought the Signature 410 watt bifacial panels last year not knowing what I was doing. I have 4 panels at 40 degree elevation on a roof deck, and another single 410 watt damaged panel on the roof with no back lighting. My sun exposure is far from ideal but better than nothing. In August, they work well from 10AM to 3PM. At this moment I am preparing to install 4 more on the roof. I have aluminum channel mounts and ran into the clamp problem. The panels are 30mm thick and the middle Tee clamps work just fine. The end clamps needed modification to hold tightly. Most clamps are made for 35mm to 50mm frame thickness. The panels are about 40x80 inches each. I mounted them horizontal lengthwise, 2 rows of 40x160 inches on that 40 degree home built triangulated frame. The low profile won't catch the wind like if the panel was mounted vertically. I got really good at making MC4 jumper wires after buying the cable kits and with strippers and crimping tool. The gender of + and minus outer sleeves with OPPOSITE gender inside contacts was confusing at first but I can do them in my sleep now. They were clever enough to make sure the internal + and minus crimped contacts are different sizes to make them goof proof. Remember PPP on the solar panel output wire... Panel Prick Positive ...the male end is positive. All solar panel MC-4 female connectors are negative. My batteries stay between 80% charge and 97% charge so far. That old upright freezer is a real energy pig and runs at about 480 watts. I have 2 chest freezers, 5 and 10 cu ft being tested right now and they run at about 77 watts each, far cry from the 1984 built freezer. Good luck!

[@lunatik9696]

The most obvious solution would be (angled) mirrors under the panels for maximum reflection. I have read white reflects well also.

[@PeaceChanel]

Thank You for All that you are doing for our Planet Earth.... Peace.. Shalom.. Salam.. Namaste .. 🙏🏻 😊 🌈 ✌ 🌷 ☮ ❤🕊

[@singlendhot8628]

We found that white solar reflective paint really helps maximize generation on our roof! We've also heard that white pebbles do a fantastic job on ground mounted installations.

[@margarita8442]

quartz rock

[@vpeters2647]

P.S. I love your real world data, there isn't alot of it out there . Your posts give me confidence in my choise of a bi-facial ground mount . I will also be experimenting with reflective material under the array . I will try and share the results here ( array install date june 2024 )

[@live1poem]

DuPont house wrat available in 9' x 200' rolls. Roll out and stake down under the bifacials. Not as reflective as snow, but it won't cover to top face.

[@whatthefunction9140]

You're channel is so underrated

[@PolioVitruvius]

Thanks! I live in the Okanagan, British Columbia, Canada. Orchard growers lay white plastic on the ground between the rows to reflect more light back up at the fruit. Might work for this too when you don’t have snow. I specify high albedo (white) roofing on flat roofs with bifacial solar arrays.

[@ProjectsWithDave]

Thanks for the info! The parallels between managing reflected light for both solar production and plant growth is very interesting.

[@kimmogensen5390]

you guys are so lucky that you have access to discounted and used panels, here in Denmark we have to pay full retail prize ,,i have these half cut bifacial 505w panels and they are really effetctive , altough i really dont get much close to nothing from them in really overcast rainy days

[@dalevanderzee4086]

I have an idea about how to maximize light to both sides of bifacial cell. Put a long cylindrical parabolic mirror underneath the cells. Place cells in a line parallel to the cylindrical parabolic mirror with the back side facing into the mirror, front side directly facing sun. This arrangement allows for rotation of the parabolic mirror with the cells to always face the sun. I bet you could significantly improve performance. There are some challenges to overcome but idea is sound. This technique would also work with regular mono cells with front side facing down. I am working on a prototype so as to get some real values.

[@reidsiebert3837]

Last winter, in Illinois, I tested my new Q cell Bifacial 420/460 watt panel with a NEP micro inverter installed. The day was bright, cold, with a fresh snow cover, and the panel was laying on a tall drift, facing south at 45-degrees. The output of the panel was being clipped at 550-watts by the NEP 600. It blew me away !!! I too have the SE optimizers, and reading an info letter from SolarEdge it mentions that any extension cord from the panel to the optimizer should not exceed 12-inches. I’m currently installing my solar system with an SE7600, a Solar City Delta H6, a half a dozen NEP 600 micro inverters, EcoFlow solar generators, and a mix of 47 panels. The Delta will just charge my Tesla. Its a real Frankenstein system. Its a retirement project, and having fun installing it myself. All parts bought off eBay and Signature Solar. No bad experiences with purchases.

[@ProjectsWithDave]

Wow, that's a great result. I'm looking forward to some winter results. The nice thing about the NEP micro inverters is you can build and expand a "Frankenstein" system and still get great results. I'm working on a video to show an install on my shed that uses a mix of panels and NEP micro inverters. Thanks for the info!

[@xeostwog]

Consider a second solar array behind the first for a reflective surface, for more utilization (suns reflection) of the rear bifacial panel.

[@redmatrix]

Have watched several of your videos in the past six months, but this one has earned a subscription from me!

[@djwaffle]

My truck topper is white and I think that factor with living in Arizona I should get pretty good results. Thank you for showing some real world results.

[@ProjectsWithDave]

You need space between the panels and the roof for the reflection to help. Watch this video on roof mounting bifacial panels: kzbin.info/www/bejne/o6vUm3apj7CIj7M

[@DanBurgaud]

VERY nice info! One of the BEST channel for Solar!

[@ProjectsWithDave]

Wow, thanks!

[@meganwinters5163]

This is why I absolutely love my bifacial solar panels! My panels face South long way, but half tip east the other tip west on short edge. Then we separated them from one another just a tad. Remarkably I get to have my garden in-between cell splits 😊🌄👍. Yes this does cause the wiring issue of different voltage throughout the day, but I have separate mppt controllers for that.

[@ProjectsWithDave]

Nice! Do you find the light passing through the panels to be a good balance between shading and sun exposure?

[@meganwinters5163]

@@ProjectsWithDave for plants "low light" plants are preferred. I haven't tried anything intensive yet, first full season with them. As far as light passing through and reflecting back (I've been told) lowers the wavelength/kelvin of that light and it can then be absorbed by the back of the panel (perhaps your tools can confirm this?). This was very evident our first snow fall. Cool panels plus light reflection lead to gained overall production. I noted that fresh wood chips in the garden are ok for this, but was thinking white sand, shell or stone would have been way better🤔. Hope this helps!

[@ProjectsWithDave]

Thanks for the response. I'm looking forward to evaluating different reflection surfaces and winter performance.

[@tommak6516]

Now your setup is really a great thing. Probably the BEST I have heard of as far as an over efficient use of resources. But my question is does the tipping increase panel efficiency or is it only to facilitate the garden. What is the east/west tip n degrees? What exactly is the spacing?

[@meganwinters5163]

@@tommak6516 please forgive my absence; this is honestly a trial and error kinda ordeal for each application. As mine is mostly setup for power production between the splits, however I like to grow lower light plants under my panels. But I do grow higher light plants between the two arrays. As for the tilt: it's going to be whenever your latitude is in degrees & then don't be afraid to split the difference between summer & winter seasonal efficiency. Personally I set mine closer to the middle in degrees & separating the panels apart approximately 2 ft. I get good production this way both reflected light to bifacial and ample plant growth. Hope this helps you!!! 😊🌞👍

[@droneanders7349]

Thanks Dave for a really god explanation on the differens. We have developed a system in the Norwegian market where we combine the panels (650Wp) with racks and feet for racks and at last a roof membran to simulate snow (Albedo=0,63). The first project (standing for 1 year) show us a Yield 1,3. This is only for big (and flat) roofs. If you want some pictures, let me know. Brg Anders

[@ProjectsWithDave]

Sounds like you have made a plan to intentionally maximize your output. I'd love to see the pictures. Thanks!

[@SolarTechFL]

I always recommend bifacial, it gives me more buffer on yearly energy output

[@jc021286]

for reflection tests: Water underneath, see what the refraction of water does to the bottom side. Simple white underlay: tarp or spray paint the ground. I'm more partial to something more eco minded than spray paint.

[@lorenzodelacruz1887]

Great technology update. I finally looked up San Tan and found I am only 5 hrs away. My son live s in Gilbert so I could throw 2 birds with one stone. Thanks for your research, you're a great man Charlie Brown! or Dave

[@ProjectsWithDave]

Shipping adds a lot to the cost of panels so that's great if you can pick them up yourself... and visiting family.... it's a win win : )

[@tomschulze6206]

Hi Dave, another great Video, I just received 21 CS 450 WATT panels from Santan, almost had the same unloading problem that you did. The truck driver had a powered pallet jack and almost run it off the back of truck, lucky I had my skid steer with forks and got under the pallet before he dumped it. I am building my own ground mount, and putting up a 31 foot car port and using one side of the verticals of carport structure to attach Unistrut @ 30 degree supports for my mounting rails to attach to . Won't get the best performance on back side, but can't beat the price for panels. Now I am looking for an Inverter, and leaning on using a Growatt 7.6 kw or 10Kw as to not get into clipping hybrid inverter, they seem most reasonable priced and have a battery backup option that can be added latter.

[@ProjectsWithDave]

Using panels to serve as a roof and power is a great strategy. If your orientation isn't ideal, you won't likely make much use of the 10kW inverter. You will probably be fine with the 7.6kW.

[@KD0CAC]

I see some of these types -- collect from both sides , or panels - all the installations use a reflective panel on the north side , basically forming a triangle , reflections from across the freeway from me look gold .

[@MrRichBenn]

These make sense for ground mounts for two reason. First, wiring becomes easy as ground mounts can be used with string inverters without rapid shutdown(optimizers,micro-inverters). Second, one can add white gravel on the ground to get 20-30% extra power. On a roof mount, neither of these things are possible. Doing the math, ground mounts with string inverters and bifacial panels are the lowest cost/watt option, at least at the time I checked. Pretty much pays for the trenching and racking, a normal disadvantage to ground mounts.

[@jec_ecart]

You could put mirrors on the ground to maximise back side irriadiaton. Even painting the terrace bright white helps.

[@hnag1907]

To get more power from Bifacial panels try using a mirror to reflect more light to the second surface.

[@pativey8674]

Great Vid thanks for taking the time to give us the great breakdown in real world situations

[@ProjectsWithDave]

Thanks! No problem 👍

[@jerrytipps9278]

I think you should mount them vertical with horizontal or angled mirrors/reflective material mounted under to help light both sides

[@pizpower]

yeah, if you could test this also with reflective paint would be great.

[@Jenan_Tahnik]

Be interesting to see if the BiFacial panels shed snow quicker since they're likely to heat up quicker in lower light conditions.

[@ProjectsWithDave]

I'm also very curious, I'll let you know when I get the results.

[@d-boyzeighteenhundred]

@@ProjectsWithDave any updates ?

[@ElationProductions]

@@ProjectsWithDave Yeah, I'm curious if the perform better in winter months too when they can get more light underneath from reflected snow. I live in Illinois, so really wind power would be a better option, but solar is going to be easier of an install and serve as an awning of sorts too.

[@kureikurashi7528]

The 66% output you saw from the back is called the bifaciality factor which is typically at 0.6-0.7. The 30% gain is the additional irradiance available for the panel through the backside. Other than that, good video.

[@ProjectsWithDave]

Bifaciality seems like a more precise spec for manufactures to list than bifacial gain. Although, I guess that might lead people to believe they could get more out of a panel than is actually realistically possible and they should be directly linked.

[@Hybridog]

I live in Austin TX and have been thinking about bifacial panels for my future system. I have imagined this scenario: My install would be roof mounted. I would install a white membrane roof instead of shingles. Then I would contruct a mounting rig that holds the panels probably a foot above that white surface probably using trusses of some sort. Then the panels would be placed in a checker board pattern or in vertical rows leaving large areas unblocked for sun to bounce off the white roof and onto the back side. My roof faces south so the orientation is good.

[@ProjectsWithDave]

I'm sure you would get improved gain with that setup, but I don't think it would be enough to justify the extra materials and effort.

[@TheDjranier]

I bought 72 of the same panels from San Tan, the delivery truck broke 17 of them on one pallet. San Tan shipped me out another 17, and I received them in about 2 weeks. Just had to salvage the broken ones. making over 28KW in Florida.

[@ProjectsWithDave]

Wow! That's a lot of broken panels. I'm glad you were able to get it worked out. 28kW in Florida, that should do very well for you!

[@TheDjranier]

@@ProjectsWithDave I’m powering my property, and sold back 26 MW. Little over $1,000 back. My break even point will be right at 7 years looks like.

[@titusm9837]

Thanks for your tests. Maybe a white cloth on the ground? (it would mimic the snow:))) or course some mirrors should help a lot. I guess this type of panels would work better on a white roof.

[@oceanside2152]

The most efficient way.. is at the correct angle for the season (6 angle positions, 6 up, 6 down ) and tracking the Sun, east to west.. Which is what I build.

[@vpeters2647]

The issues with the pannel thiskness and cable length are a function of the manufacturer, not because they are bi facial . Aptos makes a bi facial with standard thickness and 1 meter cables, they just cost more than some odd commercial brands . You have to weigh the cost of cable extentions when pricing pannels , as the cabling costs can add up .

[@RandomActsOfMadness]

Thanks for such a thorough video! For a winter test I’d like to see an ‘agrivoltaic’ version tested, with vertically mounted bifacial panels. No snow cover and nice irradiance on both sides. Do both south facing and west-east facing panels. Also, try out bifacial panels on a greenhouse roof, or even as a substitute to the normal roof glazing, as getting rid of any backing would help with thermals. At peak sun hours greenhouses get to much irradiance anyway, most greenhouses have to vent the heat away.

[@ProjectsWithDave]

Thanks for adding some more testing ideas.

[@Umski]

This kind of reminds me of the benefits of thin film panels over monos - I persuaded my installer to do half and half to prove the point and I have been getting 4-5% better performance from the the TFs on the same roof - that said they take up more space per kWp and cost more to install due to needing extra hardware. These bi-facials seem like the best of both worlds...

[@SFzip]

use white landscaping pebbles to increase ground reflection

[@martyhanson2915]

To prove the ambient light theory, it would be interesting to mount one of your single sided panels upside down and see how much power it produces

[@ProjectsWithDave]

I like that idea, I might try it. The problem, is it may not be enough power to start the inverter.

[@keithbrookshire]

You could get more light to the backs of the panels by laying a layer white of tyvek on the ground. Gray or white gravel would be more permanent.

[@gregandersen8475]

Thanks for doing this research! It is interesting with bi-facial, half-cell, different bus bar designs, and microinveters how much better panels are with shade and how much more real efficiency they show. Those NEP 600s are clipped at 390W per PV input, you may have had more! I am looking at doing a similar system with AP Systems DS3s and the Aptos 440w bifacial from Signature Solar, which also may experience clipping! The one thing that I am still trying to figure out is racking, do you like your Ready Rack system? Would you have gone with this system if you were doing things over again? I'm looking to do a ground mount with 30 72-cell panels, I would love to have it seasonally adjustable tilt and don't care about aesthetics. However, it seems like tilt adds too much money and these static mounts are likely going to be the best bet.

[@ProjectsWithDave]

I do like my racking system and I would go with it again. There is a single pole system with manual tilt adjustment one of my friends is installing that would do what you want, but it requires special equipment to drive the posts so it would be more expensive. I only connected one panel to each NEP microinverter so there was no clipping in my results. The BDM600X is capable of 580W output per inverter. I got the same result from the microinverter and the optimizers.

[@chrissinclair8705]

Just put an angled mirror behind the panels to reflect the sun onto the back, make sure it's far enough away to let the morning sunlight hit the panels naturally and you're good.

[@rolandrohde]

These are surely ideal for solar fences and so on. On a roof the effect is surely small, but better than nothing.

[@ProjectsWithDave]

Roof installation is likely to have very little benefit, but I plan to check that later this year.

[@NeverTakeNoShortcuts]

I just installed 20 480 watt panels at my cabin. The weight issue is no joke. You need 3 people to install these. You need to pay attention to the voltage in cold weather when you design them so you don’t overvolt your charge controller.

[@ProjectsWithDave]

Yes, that's a good reminder. Cold weather is when you will see the highest voltage.

[@Bowlmark]

If you have panels that do not face directly south then you can make a swivel base with an attached convex mirror (like on truck side-view mirrors but larger) behind and above the mounted panels. This will allow the unobstructed sunlight to reflect and spread out to the back of the panels. The vertical angle of the mirror should be downward based on the distance behind the panels. The horizontal angle can be adjusted via the swivel base every week or at will. This can also be done with south facing panels but the angles & size of the mirror would be determined based on your location. It may require some calculation and DIY with the swivel base setup but that is a small price to pay for increased solar production and instead of buying more panels.

[@ecoworrier]

Put something reflective on the ground behind them, or just paint the ground white. That should increase the irradiance

[@ssoffshore5111]

Great info, thanks! With that said, I'm not sold that they will make much of a difference on a typical asphalt roof installed at normal installation heights, especially panels not located on the edge of the array.

[@ProjectsWithDave]

I would not expect them to do well in that situation. I would not pay extra for bifacials to install them on a dark asphalt roof. I am doing some testing in what I would consider to be a "best case" scenario with an install on my white shed roof. You can see that install video here: kzbin.info/www/bejne/j2myeKuaf56Wi5o

[@marcfruchtman9473]

A really great video comparing bifacial vs standard single face panel. Thank you for making this. [subscribed]

[@marekkaletka6746]

Great presentation, thanks. Why not give those rescue blankets a try? Not sure about hot summer days, but in winter they should help with snow melting, as they are particulary good at reflecting the infrared part of the spectrum. And even the good ones cost next to nothing.

[@LawpickingLocksmith]

Thanks Dave! Finally a great explainer!

[@TRS-Tech]

You cannot get the bifacial panels in the UK for any money. In fact you have easily 10x the choice at better value over the pond. I personally think that the UK government dont want PV over here, they won't be able to rip us of as easily if they do. Looking at your market and product range in the US it goes against the supposed fact that the US is supposed to not care about alternative energy ! If you still have a test rig it would be interesting to try a couple of tests.... 1. I suspect the rear set of cells may come in on a seperate terminal in the diode box, if so it would be interesting to log the rear cells alone just to see what they can generate. 2. I would love to know what you would get from the bifacial if you could borrow a mirror to put under them of even aluminium foil just to see the difference. Thanks for the great work you put into your videos and the data you compile. Keep up the great work :)

[@ProjectsWithDave]

Thanks for the suggestions, hopefully I can get back to some more bifacial testing after I get through some of my current projects.

[@JarredSutherland]

I picked up 20 of these 445W Canadian Solar panels for my array that will be going in soon.

[@ProjectsWithDave]

Nice!

[@aleezavega6331]

Place a mirror on the ground underneath it and make sure the light is reflected back onto the panel. That might work

[@duncandomey8199]

Build near waters edge or over water, that will give you more reflection.

[@mikudxman7662]

make the underside of the solar array sand for the xtra reflection. sand snow and water are all good reflective things but the most realistic is having a good sandbox.

[@Slick85]

As someone mention Mylar for a reflective surface would be interesting, but with the added maintenance of keeping it clean it adds a lot of work and a greater leap in cost than something like white landscaping rock. I would be interested in the performance of something more feasible like white gravel. If you have time to test it I’d love to see the results.

[@ProjectsWithDave]

Although white rock is much more practical, Mylar is easier to test, so I plan to start there.

[@Dirt-Diggler]

Great in depth video chap 👍 Most of the bifacial panels I've seen fitted in the UK are on vehicles and the used a mylar sheet under the panels to reflect the light that passes through 🤔 adds to the expense on a large array but is more feasible on a small scale. Again really good video 👍

[@ProjectsWithDave]

Thanks! Interesting use case, thanks for the info.

[@stevepailet8258]

just imagine for a moment if you were using these panels in an agricultural setting where you mount the panels relatively flat but 14 feet off the ground so you can get tractors under the panels. I would imagine that the actual output would stay much higher during the course of the day

[@sjones9553]

I recently bought (not yet received) Jinko Solar bifacial panels. I live on a hill that is facing south. The hill is a corn field. I live near London Ontario. In the winter when the field is covered in snow. So with the sun lower during the day I am hoping the slope behind the rack mounted panels will reflect the light into the back side of the panel better than a flat land setup.

[@ProjectsWithDave]

Yes, it will likely have a significant effect. It would probably be beneficial to mount the panels a little more vertical than typical. You will shed snow more easily, and since you have bifacials you will still get good performance in the summer.

[@c-ourage486]

Has there been any data about the durability of the sealing on bifacial panels? I am especially curious about the back keeping its seal/structural integrity for decades of use, if exposed to the winter weather/elements facing north and enduring freezing and thawing moistures, that can often come interspersed with significant arctic winds gusting too. Thanks for all you've provided here so generously and accessible. It's not "everyday", Dave, that such a delightful and valuable resource is made so available to me and my projects.

[@ProjectsWithDave]

Thanks for the encouragement. I have seen a lot of failures for standard back sheets, but nothing for glass. My expectation is a panel with glass on both sides is far less likely to have sealing issues than one with a standard back sheet. In this video I talked about some of the back sheet failures you will find in the used panel market: kzbin.info/www/bejne/lXmuiGqjrLWcg6s

[@backtothepast1850]

I have Canadian Solar 445 watt bifacials. I've had as much as 533 watts on a 40 degree midday in April. I have a very light colored limestone gravel below my array

[@ProjectsWithDave]

Nice!

[@cosmiccharlie8294]

If you had a row of them with spaces between they would wrok well in the winter with the snow relecting the light. Even better on a South facing hillside.

[@ProjectsWithDave]

Gaps would improve the reflection, but difficult to manage with the racking.

[@benjones8977]

It sounds like ground mount is a much better way to get production then rooftop. How about trying some reflective materials underneath the bifacials? Reflectors or mirrors.

[@ProjectsWithDave]

I plan to try a white steel roof later this summer. Mirrors would likely be helpful, but delicate and hard to position. I was thinking mounting with a pond backdrop might offer good reflection.

[@GoldenBranchesTCG]

Great video, Dave.

[@adancetogo45]

Dave, regarding getting more light behind "bifacial" panels. How about taking the top row of panels and placing them 6 inches higher on the support rack, then take the bottom row of panels and lower them by 6 inches on the support rack. This would create a 12 inch gap between the top and bottom rows of panels and would allow direct sunlight to strike the area behind the panels. If you had a series of highly reflective surfaces under the panels, like a painted white surface, and if it were angled to reflect the sunlight up to the bottom of the solar panels, I believe that would significantly increase the energy output of the bifacial panels. And yes, perhaps the vertical racking might have to be extended a bit, but the added cost might be very small.

[@ProjectsWithDave]

That's a good idea. I think you would see some benefit from that strategy. The racking loading would need to consider the additional forces from placing the modules higher up.

[@adancetogo45]

@@ProjectsWithDave You are right about the addition torque at the top of the panel rack, but the 12 inch space in the center of the array would substantially reduce the wind loading on the face of the panel array. I think this reduced wind resistance would more then off set the loading at the top.

[@Morris1581]

Best testing i ever saw. Thank you ❤️👍🏻

[@icecreamtruckog3667]

Instal the bifacial panels in vertical orientation where at mid day peak heat the panel is not getting any sun, instead of at an angel to capture the max of light at mid day.

[@ProjectsWithDave]

You can see the winter result for vertical panels here: kzbin.info/www/bejne/a3K5gGR_rst0b68

[@nathanedmunds9802]

Put a large mirror or silver reflective fabric beneath the panels on the ground, and put a mirror behind the panel at about about 2 times the tilt angle. Raise the bottom edge of the panel to at least the length of the to allow more light to shine beneath the front edge. The panels may get too hot in the summer, but should over perorm in the other three seasons.

[@d-boyzeighteenhundred]

A mirror and silver actually eat light i believe white is the most reflective

[@firedog1116]

Mylar silver film is cheap to buy in rolls and are excellent reflectors for your backside experiments.

[@ProjectsWithDave]

Thanks for the suggestion.

[@SuperMike-WonderWendy]

A mirror on the ground under the solar panels at the same angle as the solar panels would be cheap and easy . It has to magnify the amount of light on the back so it has to increase performance . Only down side is the amount of heat it would create .

[@ProjectsWithDave]

Also, mirrors generally don't have tempered glass and would be at a high risk of breakage.

[@oby-1607]

Since these are bifacial, it would be interesting to see the long term durability and output over the years compared to the standard versions. Hopefully it will be good for the long term but usually greater gains are at the price of greater losses somewhere else.

[@ProjectsWithDave]

Time will tell, but I expect the bifacial panels to have less degradation over the long term since the back side should degrade very slowly with little direct sunlight.

[@jensschroder8214]

In Germany, bifacial panels are considered non-flammable. Normal panels with film on the back are classified as potentially flammable. This is important if the neighboring house is attached directly to your house and with normal modules there are certain distances.

[@ProjectsWithDave]

Very interesting! Thanks for sharing.

[@gospeltruth5634]

The East/West panel production argument depends upon the location. I have 3 roof faces ... 1 90 degrees Az, one 180, and one 270. My East facing panels produce more daily that the other 2 faces. Not by much, but by a little. No shading on any strings and I use optimizers.

[@ProjectsWithDave]

Very interesting. I suspect heat may be a significant factor for you, with a roof mounted system in Az. The East facing panels are picking up their sunlight during the coolest hours of the day.

[@whatever_12]

Can you try setting up a test with some type of reflector.. Like outdoor aluminum theremal insulation, white acrylic roof costing or cool metals roofing under the panel.. It might work great on flat roof in my opinion

[@ProjectsWithDave]

I'm currently testing on a white metal roof. Results will come in a few months.

[@mohd.saifullahmajid6029]

Hmm... This is very informative. Perhaps can experiment the effects of different type of surface for the ground-mounted bifacial panels. Dirts, grass, gravel, etc..

[@ProjectsWithDave]

I'll have some snow results coming soon....